Flapper valve

ABSTRACT

A flapper for a downhole valve including a surface configured to substantially geometrically mate with a tubular section within which the flapper is mounted when in an open position. The surface reduces an amount of fluid that can exist between the flapper and a housing member thereby reducing the effect of turbulence on the flapper. The geometrically mating surface may be a hard surface that is configured to mate or may be a softer surface that will self conform.

BACKGROUND

In the downhole drilling and completion industry flapper valves havebeen used for an extended period of time. Such devices are usefulwhenever it is necessary to cause a fluid to move into the downholeenvironment from a remote location such as a surface location. Flappervalves come in a number of forms but not uncommonly are configured astubing retrievable injection valves (TRIV), for example. Such valvesoften comprise a flapper that articulates and a flow tube thattranslates through a position occupied by the flapper when closed,thereby maintaining the flapper in an open position throughout theinjection cycle. The open position is so maintained by the flow tubestructurally pushing the flapper out of the way (causing rotation aboutits pivot) when the flapper valve is in the open position. While suchflapper valves work well for their intended purposes, improvement isalways desirable whether that improvement be in performance, costreduction or both.

SUMMARY

A flapper for a downhole valve including a surface configured tosubstantially geometrically mate with a tubular section within which theflapper is mounted when in an open position.

A downhole valve including a housing; a flow tube moveably disposed inthe housing; and a flapper articulated to the housing, the flapperincluding a surface configured to substantially geometrically mate witha tubular section within which the flapper is mounted when in an openposition.

BRIEF DESCRIPTION OF DRAWINGS

Referring now to the drawings wherein like elements are numbered alikein the several Figures:

FIG. 1 is a schematic view of a flapper valve as disclosed herein in aclosed position.

FIG. 2 is a schematic view of the valve of FIG. 1 in an open position.

FIG. 3 is a schematic view of a portion of an alternate embodiment ofthe flapper valve disclosed herein, the portion circumscribed by line3-3 in FIG. 2.

FIG. 4 is an alternate embodiment of a flapper valve in a closedposition.

FIG. 5 is and alternate embodiment of a flapper valve in an openedposition.

DETAILED DESCRIPTION

Referring to FIG. 1, valve 10 such as a flapper valve includes arelatively short flow tube 12 disposed in operable communication with arelatively short housing 14. The flapper valve 10 further includes aflapper 16 articulated to the housing 14 at a pivot point 18. A seal 20is disposed at the housing 14 and positioned for interaction with theflapper 16 when the flapper valve 10 is in the closed position. Morespecifically, the seal 20 ensures that the flapper 16 when closed willform a fluid tight interface with the housing 14. Such seals are commonand tend to be relatively soft. This makes them vulnerable to flowcutting and hence they require protection. Protection in the illustratedconfiguration is provided by a flow tube that need be only long enoughto extend past the seal 20 when the flapper 16 is open. This isillustrated in FIG. 2. Further, one of ordinary skill in the art willrecognize that as illustrated, the flow tube would not function to openthe flapper 16 as is the case in many prior art valves but rather stopsshort of interacting physically with the flapper 16. In thisconfiguration, it is the flow of injection fluid that opens andmaintains the flapper 16 in the open position. The flow tube in thisconfiguration then has only to protect the seal 20, which it does in theposition illustrated in FIG. 2. It is noted that it is possible to applythe concepts herein to a valve with a longer flow tube that also hasfunction to open the flapper 16 but such function is not necessary tothe teaching herein. In either case, an extension spring 22 in operablecommunication with the flow tube 12 and the housing 14 willautomatically move the flow tube 12 to the operational position when theflapper 16 is opened, that opening being due solely to flow or to flowin combination with another opening impetus.

The flapper 16 itself comprises an erosion resistance that is eithersurface concentrated such as in the form of a coating or a surface layeror may be erosion resistant for a greater percentage of the flapper 16,including but not limited to the entire flapper being composed oferosion resistant material. This configuration allows the use of thevalve 10 with high injection flow rates without a flow tube 12 beinglong enough to cover the flapper 16.

Because the flapper is exposed to flow during use of the valve 10 due toa short flow tube, fluid dynamics considerations are of importance whenthey are traditionally irrelevant to the flapper. The fluid flowing pastand in contact with the flapper 16 causes turbulence behind the flapper16 adjacent an inside surface 24 of a tubular 26 in which the valve 10is installed. The turbulence can cause the flapper to move into the flowstream and not stay against the surface 24. This is a hindrance toinjection and hence is to be avoided. The problem is exacerbated byhigher injection rates. In order to address this issue the inventorhereof has determined that the effect of turbulence with respect to itsability to move the flapper into the injection flow can be minimized byreducing the fluid volume between a surface 28 of the flapper 16 and thesurface 24. It is to be noted that the surface 28 may be of the flapperitself or may be of a material attached to the flapper. In oneembodiment, the surface 28 is formed by providing a conformable material30 attached to the flapper 16. The conformable material 30 will assumethe shape of the inside surface 24 upon contact therewith and preventany significant turbulent fluid from urging the flapper 16 away from thesurface 24 during injection. This embodiment allows for irregularitiesin the surface 24 to be accounted for without knowing what thoseirregularities might be. More specifically, the tubing string in whichthe valve 10 is installed may have experienced flow cutting or erosionor may have become deformed during run in and resultingly does notnecessarily present a cylindrical geometry at the surface 24 for apreconceived surface 28 to geometrically mate with. In such situation aconformable material 30 provides a wider range of functional success inreducing any potential volumes within which turbulent fluids mightotherwise act. Conformable materials include but are not limited torubber, nitrile, foams (including shape memory foam), etc. In otherembodiments, the material may be a nonconformable material attached tothe flapper or may be the flapper itself. In such cases, the materialmay geometrically mate well with the inside surface 24 and performsubstantially as does the conformable material or may geometrically mateless well with the surface 24 but in any event, the material 30 will beformed to substantially geometrically mate with the surface 24 andaccordingly will substantially displace turbulent fluid from the volumedefined between the surface 28 and the surface 24. Due to the reductionin turbulent fluid in this location, impetus on the flapper 16 to moveinto the flow path of the injection fluid is reduced or eliminated.

Still referring to FIGS. 1 and 2, the torsion spring 19 operates tooppose the force of flowing injection fluid but without sufficientenergy to overcome the force of the flowing fluid. The flapper 16 thenwill be opened by the flowing fluid but will close automatically uponcessation of flow of the injection fluid. In one embodiment, the torsionspring is configured with a greater spring force than the extensionspring 22 such that the flow tube may be pushed back to its unactuatedposition by the flapper 16 through the impetus of the torsion spring 18.

In addition to the foregoing, and referring to FIG. 3, the flapper mayfurther include a magnetic component 32 that is attractive to the tubing26 or to another magnetic component 34 disposed in the tubing 26. Themagnet(s) either singly or in combination act to maintain the flapper 16in contact with the surface 24 thereby reducing any available volumeinto which fluid may flow which consequently reduces any possibleimpetus for the flapper 16 to move into the injection flow. In addition,because of the attractive force of the magnets, it is in one embodiment,it is not necessary to have the surface 28 or material 30 of FIGS. 1 and2. FIGS. 4 and 5 illustrate such an embodiment. With respect toreleasing the magnetic attraction of any of the embodiments herein thatinclude magnetic field generating components whether of opposing polesor only one sided and attractive to a ferrous material, a sliding actionwill be used. For an understanding of such an action and one embodimentof a configuration capable of producing the sliding action, see FIGS. 4and 5 and the description thereof hereinbelow.

Referring to FIGS. 4 and 5 simultaneously, an embodiment of a flappervalve 100 that ensures the flapper stays in the open position regardlessof turbulence is illustrated. Illustrated is a housing 101 having amagnet housing 102 disposed therein. The magnet housing is axiallymovable within the housing 101 and is fluid sealed thereto by one ormore seal 104. The magnet housing 102 supports a magnetic fieldgenerating component 106 that comprises a permanent magnet or anelectromagnet. The magnet housing 102 is biased by a compression spring108 that may be a coil spring as illustrated or any other type of springthat provides resilience in compression. The spring 108 is maintained inposition by a shoulder 110 in the housing 101 and a flapper sub 112 thatbounds the annular space in which the spring 108 is located. The flappersub 112 is a non movable component that is at least partially composedof a nonmagnetic material, the part being where a magnetic field wouldneed to pass through the sub 112. This area is labeled 115. The sub 112is anchored by suitable means 114 at recess 116 in housing 101. Thesuitable means 114 may be one or more fasteners such as threadedfasteners, welding, adhesive, press fit, etc. at an end of flapper sub112 opposite the means 114 is a pivot 118 and torsion spring 120 thattogether allow pivotal movement of a flapper 122 and a bias of theflapper 122 to its closed position (illustrated in FIG. 4). Adjacent aportion of the flapper 112 is a flapper seat 124 and a seal 126 thereat.Seat 124 may be attached to flapper sub 112 at and by, for example,thread 128. A flow tube 130 is positioned radially inwardly of the seat124 and is moveable therein. The flow tube is connected to a tensionspring 132 that is also connected to the flapper seat 124. The tensionspring 132 tends to bias the flow tube toward the flapper 122 such thatwhen the flapper 122 is in an open position the flow tube will protectthe seal 126 from erosion due to fluid flow. The flow tube 130 needmerely extend a small distance past the seal to provide this protection.It is to be understood that the tension spring 132 is sufficient inspring rate only to move the flow tube 130 to the protective positionbut is insufficient to prevent closure of the flapper 122 based uponinput from the torsion spring 120. This configuration ensures that theflapper 122 will close properly when it is supposed to without the flowtube interfering with the closure. Finally, the flapper 122 is providedwith a magnetic field generating component 136, which in one embodimentcomprises a permanent magnet but may be configured as an electromagnet.In one embodiment the exposed surface of the component 136 will be of anopposing magnetic pole to the exposed surface of the component 106. Itis inconsequential which one of the two is north or south pole oriented.

In operation, a fluid 138 is applied in the direction of flow arrow 140toward the flapper valve 100. The fluid 138 forces the flapper to swingopen (position depicted in FIG. 5), and simultaneously through fluiddrag, moves the magnet housing 102 in the same direction as fluidmovement. This action causes the magnetic field generating component 106to move along with the magnet housing 102 to a position where thearcuate movement of magnetic field generating component 136 will be inregister therewith, the movement of component 136 being dependent uponthe pivoting movement of flapper 122. Because the two components 106 and136 are aligned and positioned in proximity to one another as well asbeing oppositely poled, the flapper is magnetically held in the openposition and hence out of the flow of fluid 138. By design the springforce of the torsion spring 120 is insufficient to overcome the magneticattraction between components 106 and 136 and therefore is of noconsequence with respect to maintaining the flapper 122 in the openposition. As one of skill in the art will recognize, the flapper of avalve of this type must close when injection is stopped. This action isalso unimpeded because as soon as the fluid drag on the magnet housing102 is relieved, secondary to a pause in the flow of fluid 138, thecompression spring 108 will elongate and force the magnet housing 102 tomove to the closed position of FIG. 4. This will cause the magneticfield generating component 106 to slide away from the magnetic fieldgenerating component 136 thereby substantially reducing the attractiveforce therebetween. The flapper is hence free to close under the impetusof the torsion spring 120.

In other embodiments, it is noted that the magnetic field generatingcomponents need not be on both sides of the resulting attractiveinterface but rather one could simply be a magnetically responsivematerial such as a ferrous metal. A reduced attractive force wouldresult but if the component used has a sufficiently potent field, itwould still function as noted above. Sliding action would still be usedto break the interface wither by moving a nonmagnetic material intoproximity with the components while the magnetically responsive materialis slidingly moved away or a configuration where a sliding movementwould simply position the field generating component farther away from aresponsive material such as by sliding one of the structural featuresdescribed in a direction that allows a recess to be aligned with thefiled generating component. In such an embodiment the recess wouldposition a responsive material far enough away from the field generatingcomponent to reduce the attractive force to a magnitude less than aclosing force supplied by the torsion spring.

While one or more embodiments have been shown and described,modifications and substitutions may be made thereto without departingfrom the spirit and scope of the invention. Accordingly, it is to beunderstood that the present invention has been described by way ofillustrations and not limitation.

1. A flapper for a downhole valve comprises a surface configured tosubstantially geometrically mate with a tubular section within which theflapper is mounted when in an open position.
 2. A flapper as claimed inclaim 1 wherein the surface is a surface of the flapper.
 3. A flapper asclaimed in claim 1 wherein the surface comprises a material disposed asa part of the flapper.
 4. A flapper as claimed in claim 3 wherein thematerial is conformable.
 5. A flapper as claimed in claim 3 wherein thematerial is rubber.
 6. A flapper as claimed in claim 3 wherein thematerial is nitrile.
 7. A flapper as claimed in claim 3 wherein thematerial is foam.
 8. A downhole valve comprising: a housing; a flow tubemoveably disposed in the housing; and a flapper articulated to thehousing, the flapper including a surface configured to substantiallygeometrically mate with a tubular section within which the flapper ismounted when in an open position.
 9. A downhole valve as claimed inclaim 8 further including an extension spring disposed between the flowtube and the housing.
 10. A downhole valve as claimed in claim 8 whereinthe flow tube has a length sufficient to protect a flapper seal in thehousing when the valve is in an open position.
 11. A downhole valve asclaimed in claim 8 wherein the flapper includes erosion resistance. 12.A downhole valve as claimed in claim 11 wherein the erosion resistanceis supplied by a coating on the flapper.
 13. A downhole valve as claimedin claim 11 wherein the flapper material is erosion resistant.
 14. Adownhole valve as claimed in claim 8 wherein the surface configured tosubstantially geometrically mate is a surface of the flapper.
 15. Adownhole valve as claimed in claim 8 wherein the surface configured tosubstantially geometrically mate is a material on the flapper.
 16. Adownhole valve as claimed in claim 15 wherein the material isconformable.
 17. A downhole valve as claimed in claim 15 wherein thematerial is foam.
 18. A downhole valve as claimed in claim 15 whereinthe material is rubber.
 19. A downhole valve as claimed in claim 8wherein the flapper includes at least one magnetic field producingcomponent.
 20. A downhole valve as claimed in claim 19 wherein thehousing includes at least one attractively poled magnetic fieldproducing component.